commit 054922bb upstream.

The flag SCF_ACK_KREF is only set but never tested. Hence remove
this flag.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>